I stopped wearing a watch years ago, because the extra information I got from looking at my smartphone covered the overhead of pulling it out of my pocket. I've enjoyed not having something strapped to my wrist, so any of these horribly thick smart watches are going to have to provide a compelling benefit to get anywhere near my arm.
Because of size and power issues, you can't actually read or deal with anything but the most trivial issues on a smart watch. So the main value proposition seems to be that they tell you you need to look at your phone, and that's not compelling enough for me.
Apple will get some sales, from those who need their status affirming - just like the people who still wear a Rolex watch. But I'm betting that all the other smart watches disappear fairly soon.
My pick for the next real user interface revolution? Smart hearing aids, using speech as the UI. Inconspicuous, and simple to use - particularly for our affluent ageing population, many of whom need the hearing aid part anyway.